Glass sheets are conventionally made by forming a continuous glass sheet strip that is slowly cooled in an annealing lehr to provide annealing so as not to generate internal stresses that are so great as to prevent the strip from subsequently being cut into sheets of a discrete length. Conventional processing forms the glass sheet while floating on a molten metal bath of tin and then delivers the glass sheet from the tin bath to the annealing lehr for the slow cooling. Prior to entering the annealing lehr, the lateral edge portions of the glass sheet can be trimmed in a hot condition as disclosed by U.S. Pat. No. 4,749,400 Mouly et al. During the annealing, the temperature of the glass sheet strip is slowly cooled from the "annealing point" which is normally in the range of about 1000 to 1040.degree. Fahrenheit (about 538 to 560.degree. centigrade) to the strain point which is generally in the range of about 925 to 970.degree. Fahrenheit (about 495 to 520.degree. centigrade). Between 925 and 1040.degree. Fahrenheit (496 to 560.degree. centigrade) is conventionally referred to as the "annealing range". More specifically, both the annealing point and the strain point between which the annealing range extends are defined as temperatures that correspond either to a specific rate of elongation of a glass fiber when measured by ASTM Method C336 or a specific rate of midpoint deflection of a glass beam when measured by ASTM Method C598. Internal stresses of a glass sheet at the annealing point are substantially relieved in minutes, while internal stresses at the strain point are substantially relieved in hours.
During conventional annealing, the continuous glass sheet strip is supported on conveyor rolls for conveyance from the annealing point to the strain point through the annealing range. Since the glass is relatively soft at the annealing point, its surfaces can be deformed by engagement with the conveyor rolls and thereby adversely affect optical quality and mechanical strength.